Kazuki, who married Toshiko in a pre-arranged marriage, neglects his wife and spends the majority of his time with his men. Toshiko, after hearing of Toni Ciprianidestroying a Yakuza tank, hires him to destroy and humiliate Kazuki, first by having Toni steal a Yakuza munitions delivery and then destroy Kazuki's casino takings whilst being transferred. Toni later accompanies Toshiko to the opera before meeting Kazuki face to face on the top of his casino, killing him. After learning of her husbands death Toshiko, feeling remorse, commits suicide.

Trivia

During the mission A Date With Death, Toshiko states that Kazuki is a samurai. Kazuki is likely to either be a descendent of a samurai or to follow the Bushido code practiced by the Yakuza, becoming a samurai by way of practice and nickname. The official title as a military nobleman was abolished during the Meiji Restoration during the nineteenth century.

It is sometimes alluded to that Kazuki is a closeted homosexual. When Toshiko tells Toni that Kazuki "prefers the company of his men", she then asks "do you understand, Mr. Cipriani?". Toni later teases Kazuki when he says "I will enjoy thrusting my sword into you!", to which Kazuki does not respond and soon after tries to have Toni killed outside of his samurai code of honor.

Furthermore, on the game's official website, an email is shown from Kazuki to Kenji, saying he feels very guilty about something he isn't telling Toshiko. He writes "Many times, I have killed a man, afterwards, just to keep him quiet", and that "now there is someone special, but I am a man, not a rat, skulking in a sewer". Toshiko discovers the email and sends it to an anonymous forum for life advice.